两种菌体前处理方法对MALDI-TOF MS鉴定临床分离菌效果的影响

目的评价2种不同前处理方法对基质辅助激光解吸电离飞行时间质谱(matrix-assisted laser desorption/ ionization time of flight mass spectrometry，MALDI-TOF MS)鉴定临床分离菌效果的影响。 方法收集临床菌株43株，划线传代后，分别使用提取法和抹板法对微生物样本进行前处理，然后用MALDI-TOF MS鉴定比较两种处理方法的准确率和蛋白指纹图谱特征。 结果以16S rRNA/ITS RNA测序结果为参考标准，待测菌株经提取法处理后，MALDI-TOF MS鉴定革兰阳性菌、革兰阴性菌和真菌的种水平准确率分别为93.8%、100.0%和30.8%，待测菌株经抹板法处理后，MALDI-TOF MS鉴定革兰阳性菌、革兰阴性菌和真菌的种水平准确率分别为75.0%、100%和7.7%。提取法处理菌株后得到的蛋白指纹图谱中特征峰更多，信噪比更高，蛋白指纹图谱重现性更好。 结论推荐采用提取法为MALDI-TOF MS鉴定的常规前处理方法，其对建立标准的微生物检测流程，提高质谱鉴定的正确率，有重要价值。

Effect of two kinds of bacterial pretreatment methods on the clinical isolate strains identification by MALDI-TOF MS

ObjectiveTo evaluate the effect of different pretreatment methods on the identification of clinical bacterial isolates by matrix assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF MS). MethodsForty-three clinical isolates were collected and subcultured before treated by two different sample preparation methods including off-plate extraction method and direct on-plate method. And then the treated strains were identified by MALDI-TOF MS. The identification accuracy of the two methods and the peak of protein fingerprint were compared. ResultsUsing the results of 16S rRNA or ITS RNA as reference standard, the identification rates of gram positive bacteria, gram negative bacteria and fungus treated by off-plate extraction method were 93.8%, 100% and 30.8%, respectively. And the identification rates of gram positive bacteria, gram negative bacteria and fungus treated by direct on-plate extraction method were 75.0%, 100% and 7.7%, respectively. The characteristic peak in the protein fingerprint obtained after extraction was more; the signal-to-noise ratio was higher and the reproducibility of protein fingerprint was better. ConclusionIt is recommended that the off-plate extraction method for MALDI-TOF identification should be used, which is of great clinical significance for the establishment of a standard microbial detection process and the improvement of the accuracy of mass spectrometry identification.